Mobile phones and tablets are becoming increasingly used to run a variety of applications and overtaking roles formerly dedicated solely to traditional computing devices. In lockstep with the burgeoning use of such mobile devices, biometric and hands-free mechanisms to interact with the devices, such as audio recognition, continue to be developed. For example, Bluetooth and other short-range wireless technologies allow users to communicate without being tethered to the communication device. Similarly, audio and speech recognition systems permit a user to direct a device to perform some action via spoken commands.
With the advent of speech recognition systems, software developers have begun to incorporate audio passphrase recognition into multi-factor authentication systems. As such, it can be important that the audio transmitted to the passphrase recognition system is secure. Various audio security mechanisms have been developed. For example, audio digital rights management (DRM) systems have been developed to secure pre-recorded and encrypted audio. Similarly, hardware reinforced audio protection mechanisms such as Protected Audio Video Path (PAVP) have been developed. However, each of those mechanisms is directed to pre-recorded audio. As such, live audio captured via a microphone may be insecure and prone to attack.